Rain attenuation prediction model for terrestrial links incorporating wet antenna effects

Accurate prediction of rain attenuation is critical for the design of terrestrial line-of-sight link systems above 5 GHz, particularly for millimetre-wave frequency. Anomalous behaviour in the adjustment factor in existing rain attenuation prediction models is significantly greater than 1 at short distances and has been reported. To solve this problem and improve the accuracy, a rain attenuation prediction model for terrestrial line-of-sight links is proposed. The total rain attenuation described in the model accounts for the contributions of wet antenna attenuation and path rain attenuation. In addition, a rainfall rate adjustment factor is proposed. The proposed model has a root-mean-square error of 21.54% in prediction, which is an improvement compared to other existing models. Because the rainfall rate adjustment factor used in the model approaches 1 at short distances, the model can be applied to rain attenuation prediction for short-distance links. The results will assist designers to design link margins more accurately.